One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,8)(9,10,15,12)(11,16,14,19)(13,17,21,20)(18,23,22,24)(25,26,31,34)(27,32,35,30)(28,29,33,40)(36,37,38,39)(2,6)(4,8)(9,11,15,14)(10,16,12,19)(13,18,21,22)(17,23,20,24)(25,27,31,35)(26,32,34,30)(28,38,33,36)(29,39,40,37)(1,3,5,7)(2,4,6,8)(10,12)(11,14)(13,21)(23,24)(27,35)(28,33)(29,40)(30,32)(1,4,5,8)(2,7,6,3)(9,12,15,10)(11,16,14,19)(13,17,21,20)(18,24,22,23)(25,28)(26,29)(27,36)(30,39)(31,33)(32,37)(34,40)(35,38)(1,4)(2,3)(5,8)(6,7)(9,13)(10,17)(11,18)(12,20)(14,22)(15,21)(16,23)(19,24)(25,29)(26,33)(27,37)(28,34)(30,36)(31,40)(32,38)(35,39) involution — undirected(1,3)(2,4)(5,7)(6,8)(9,14,15,11)(10,16,12,19)(13,22,21,18)(17,23,20,24)(25,30)(26,27)(28,39)(29,36)(31,32)(33,37)(34,35)(38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.